Conventional iron lungs are bulky and cumbersome box-like units which require heavy power units. They can be transported only when separated from the patient and even then with considerable difficulty. Most iron lung patients are quadraplegic poliomyelitis victims and many are cared for in private homes. If it is desired, for example, to take an iron lung dependant on an outing, he must be removed from the lung and placed on a mask respirator to allow the iron lung to be loaded into a van or truck and delivered to the intended site.
In order to at least in part alleviate the inherent disadvantages of iron lungs, various types of respirator shells or half-shells have been proposed. These are intended to be worn virtually as an additional garment and thereby be transported with the patient. However the employment of shells for artificial respiration of paralysis patients has been less than successful in that it has proven difficult to secure a satisfactory airtight seal against the patient's skin at the upper and lower margins of the shell. The majority of prior respiratory shells have been of a type which pass over the shoulders of the patient and accordingly have separate sealed openings for the neck and arms. Reference is made in this respect to U.S. Pat. Nos. 2,270,313 (Kraft) 2480980 (Terhaar) and 2529258 (Lobe) each of which describes a continuous expansible uniformly thick neck seal of conical form to allow for varying neck thicknesses and to enhance the seal during the vacuum stroke of the respiration cycle.
In order to avoid the need for four sealed openings, two alternative arrangements have been proposed. The first of these, the so-called Monaghan technique, entails the application of a half-shell to the ventral part of the supine patient. U.S. Pat. No. 2,287,939 (Kraft) for example, described such a device having a continuous very soft resilient sealing lip or flap which extends from an inflated tube at the edge of the rigid half-shell.
The second alternative is the provision of a shell which extends only to a single upper opening in the vicinity of the chest, but this involves the difficulty of sealing across the chest area.
U.S. Pat. No. 2,241,444 (Bower) refers to an arrangement of this kind and also describes side clamps holding the shell sections together. Bower also describes in some detail the custom manufacture of the shell sections from initial plaster cast of the patient's torso. The sealing rings are simple internal gaskets at the peripheries of the shell sections.
U.S. Pat. No. 3,368,550 (Glascock) describes and illustrates upper and lower sealing lips which extend inwardly onto the patient's body from outstanding locating flanges and which are held in sealing engagement with the skin by respective bands.
Reference is also made to U.S. Pat. Nos. 2,833,275 (Tunnicliffe), 2,456,724 (Mullikin) and 2,588,192 (Akerman et al) for further examples of prior shell--type respirator devices.
It is an object of the invention to provide an improved portable negative pressure respirator shell capable of satisfactory airtight sealing engagement with the skin at least during the vacuum application stroke.